This invention relates to a roll formed, sheet metal beam which is used, primarily, in a heavy-duty, load-bearing rack, such as the type of open-frame racks used for supporting pallets and the like.
A pallet rack or heavy-duty support frame is disclosed in my U.S. Pat. No. 4,760,682 issued Aug. 2, 1988, for a "Tubular Rack Beam and Method of Making Same". By way of example, a rack frame is generally formed of a number of upright posts which are interconnected by horizontal beams. The beams form shelves upon which heavy loads may be positioned. For example, a loaded pallet or large, heavy containers, may be placed upon the horizontal beams and supported thereon using material handling equipment such as fork trucks or the like. Alternatively, slats or shelf forming boards may be positioned upon and extended between opposing beams to form shelf-like surfaces for supporting loads.
Typically, the vertical posts are made of square or rectangular in cross-section tubes formed of steel or the like sheet metal. The horizontal beams which interconnect the posts, also are usually formed of strips of sheet metal, such as steel, which are bent or roll formed into tubes. These tubes may be generally square or rectangular in cross-section or have a cross-section which generally approximates a square or rectangular cross-section. In the past, one form of beam was made of two channel long channels which were arranged with their legs interfitting. The two channels were welded together to form a unitary beam. In my above-mentioned U.S. Pat. No. 4,760,682, the beam is disclosed as being formed of two, generally channel shaped pieces, which are interlocked together frictionally or mechanically and, also, are secured together by an adhesive.
Another form of prior beam has been made of a single strip of sheet metal which was bent or roll formed into a tubular shape. The opposite edges of the strip were either overlapped and welded together or were bent into edge beads or flanges which were arranged adjacent one another and welded together.
The invention herein is particularly concerned with improving a single strip sheet metal type beam so as to improve its anticipated strength while simultaneously reducing the cost of manufacturing this beam. Since substantial quantities of this type of beam is used in industry, particularly in storage facilities in factories or in warehouses, an increase in the strength of such beams, which permits using a smaller cross-section or a thinner gage material, can substantially, reduce costs. Likewise, costs can be reduced by the elimination of the usual welding procedures.
Thus, this invention is concerned with improving the manufacture and construction of a tubular, sheet metal beam which is typically roll formed out of a long, single strip of sheet metal.